An exhaust driven turbocharger may be used with an internal combustion engine to compress air delivered to the engine's intake air system. The turbocharger may include a compressor rotor driven by a connected turbine rotor. The compressor may include a housing that channels intake aft and the turbine may include a housing that channels exhaust gases. The compressor housing may be spaced apart from the turbine housing by a bearing housing containing bearings that support a shaft connecting the turbine rotor to the compressor rotor.
The compressor rotor, the shaft and the turbine rotor may rotate at speeds that approach hundreds of thousands of revolutions per minute. In addition, the turbine rotor operates in a high temperature exhaust gas environment, wherein heat may be transferred to the other turbocharger system components. Under these harsh, and increasingly demanding operating conditions, the lifespan of a turbocharger is expected to match that of the engine with which it operates. To accomplish that challenge, the design of a turbocharger and its components must be robust to survive as expected, while still being cost effective. As a result, a turbocharger is designed to exacting tolerances and standards.
To reduce friction in the bearings, the bearing housing may include an oil delivery system to provide lubrication. Oil may be provided by the associated engine's pressurized oil delivery system and may be channeled through the bearing housing to the bearings and other rotating parts. The oil may then be collected and allowed to drain back to the engine's sump. Maintaining the integrity of the lubrication circuit is essential so that the oil level in the associated engine is not depleted, and so that oil does not enter unwanted areas.